1. Technical Field
The present invention relates in general to an improved method and system for data processing and in particular to a docking device to which a portable computer can be docked and a method for controlling the docking device. Still more particularly, the present invention relates to an improved docking device for a portable computer and a method for controlling the docking device which enables the docking and undocking of the portable computer and the docking device when the portable computer is operating at either an ordinary or a reduced power level.
2. Description of the Related Art
A. Portable Computer PA0 B. Docking Device for a Portable Computer PA0 C. Docking of a Portable Computer With the Docking Device PA0 (1) If the docking of the portable computer with the docking device is attempted in an ordinary operation state or standby state (in other words, a power-on state), the power supply of the portable computer is forcibly shut down to prevent damage to the docking device hardware. PA0 (2) If docking is attempted in a suspend state, the docking device inhibits operation of the portable computer from being resumed after docking. In addition, the docking device issues a warning (usually a beep) to warn that such docking is not allowed (an operation error). PA0 (3) If the docking is tried in a power-off state, the usual operation is performed after the docking when the power is turned on (a normal docking operation).
With recent technological innovations, small and lightweight portable personal computers (or portable computers) have become widely available. With reference now to FIG. 17, there is illustrated an example of a conventional portable computer. As illustrated, a portable computer 1000 comprises a thin main body 1010, and a cover 1020 which is connected so as to be freely opened and closed with respect to the main body 1010. The cover 1020 has a pair of projections 1021 formed in the lower end thereof, whereby the cover 1020 is hinged-connected to the main body 1010. Within cover 1020, a liquid crystal display (LCD) 1022 is disposed as the display means of portable computer 1000. Further, on the top of the main body 1010, a keyboard 1011 is disposed as the input means of portable computer 1000.
Referring now to FIG. 18, the interior of the main body 1010 is depicted. The inside of the main body 1010, which is exposed by lifting keyboard 1011, is partitioned into a front section and a back section by a partition 1012. In the back section hidden by the partition 1012, the circuit board (not shown) of the computer including a CPU, ROM, RAM, system bus, and the like is accommodated. In addition, in the space in front of the partition 1012, peripheral devices such as a floppy disk drive (FDD) pack 1013, hard disk drive (HDD) pack 1014, and a battery pack 1015 are received in an removable manner.
For portable computers such as portable computer 1000, retaining portability limits the external storage and communication units which can be built in the computer. Further, when a portable computer is used on a desk top, it is very cumbersome to separately connect various cables such as the printer cable, monitor cable, and communication cable and an AC adapter. In addition, because the size of the portable computer is small, the size and number of devices which can be accommodated are limited. Thus, a docking device for a portable computer, also called an "expansion unit" or a "docking station," which support additional capabilities of the portable computer (hereinafter, simply referred to as a "docking device", whereas a portable computer to be connected and used is also simply referred to as a "host") has already been developed and is publicly available.
With reference to FIG. 19, there is illustrated a conventional docking device for a portable computer. Docking device 1100 comprises base body 1110 and a cover 1120. The base body 1110 has a support section 1111 on which the portable computer 1000 is mounted. On both sides of the support section 1111, guides 1112 are provided into which the portable computer is inserted. In the back of the support section 1110, a connector 1113 for connection of signals between the portable computer 1000 and docking device 1100 is provided. Referring now to FIG. 20, there is depicted an isometric view of the back of portable computer 1000. In the back of the main system body 1010, connector 1113 is provided for connection of signals between portable computer 1000 and the docking device 1100. As depicted in FIG. 21, portable computer 1000 slides across support section 1111 along the guides 1112 until portable computer 1000 and 1100 are docked by connection of connectors 1017 and 1113. Undocking is performed by following the foregoing procedure in reverse.
In addition to this application, for instance, in the Patent Application 3-273323, Patent Application No.3-294917, Patent Application No. 4-617, Patent Application No. 4-186411, Utility Model Application No. 3-119220, and Utility Model Application No. 3-127933, there are also described docking devices for a portable computer.
A docking device for a portable computer generally performs two major functions--port replication and bus expansion. The port replication function is achieved by providing an extension of the port signals of the portable computer in the docking device. That is, if the above-described various cables are previously connected to the individual ports of the docking device, the user can use a printer, monitor, etc., simply by docking the portable computer with the docking device, thereby eliminating the cumbersome work of separately connecting a cable for each device. In addition, the number of ports which are available on the docking device is usually larger than the number provide on the portable computer, consequently enabling more devices to be connected to the portable computer.
The bus expansion function is achieved by the docking device having an extension of the system bus of the portable computer. Since the portable computer is compact, the number of devices which can be directly connected to the system bus (for example, an ISA bus) is relatively small. Accordingly, by connecting desired devices to the system bus extension within the docking device, the portable computer can use additional devices. The devices can include, for example, an add-on HDD (for example, an IDE.sub.-- HDD), SCSI device, and a PCMCIA device. The SCSI device and PCMCIA device are devices which conform to the Small Computer System Interface (SCSI) standard and Personal Computer Memory Card Interface Association (PCMCIA) standard, respectively, (in brief, it is to be understood that IDE, PCMCIA, and SCSI are standards for connection of devices to an ISA bus), which are usually connected to the system bus through a SCSI controller and a PCMCIA controller. Accordingly, if the SCSI controller and the PCMCIA controller are provided on the system bus extension within the docking device, devices are easily added on. Thus, the main role of the docking device for a portable computer would be to supplement the functions of the portable computer which are insufficient because of its compact structure.
The connection of a docking device for a portable computer with a portable computer is usually performed by a single connector which includes all of the port signals, bus signals, control signals and the like, rather than by discrete connectors provided for the respective cables and devices. The reason for this is that it would be difficult, if not impossible, to manufacture a docking device which enabled mechanical alignment between a plurality of connectors and mechanical alignment between each pin of each connector. For example, in the above described Patent Application No. 4-291028, the docking station and the portable computer are docked utilizing a single connector formed by bundling all of the signals, as shown in FIGS. 19 and 20. Similarly, Patent Application No. 3-273323, Patent Application No. 3-294917, Patent Application No. 4-617, Patent Application No. 4-186411, Utility Model Application No. 3-119220, and Utility Model Application No. 3-127933, in accordance with the drawings attached to each specification, describe a docking device and a portable computer which are docked by a single connector.
If a docking device and a portable computer are mechanically connected by a single connector containing all of the required signals, as described above, several technical problems remain. One of the problems is to electrically connect both systems smoothly when the portable computer is in a power-on state or a power save mode such as suspend, in other words, an active state in which the power supply to the portable computer is not completely shut off.
Those skilled in the art will appreciate from the above description that the connector for connecting the portable computer and docking device includes signals having various characteristics. These signals can be classified into two categories. One category comprises port signals for connection to a keyboard, mouse and CRT, and the other category includes bus signals such as the system bus, PCMCIA control signal, IDE.sub.-- HDD control signal, and FDD signal. One criterion for such classification is that the port signals can be connected or disconnected even in a power-on state (namely an active state), whereas the bus signals cannot be connected or disconnected when active. The reason for this distinction is described below.
A port signal is usually communicated to the system bus through a device controller (for instance, a keyboard controller for the keyboard, and a video controller for CRT). These controllers, if simplified, consist of an interface circuit for communication with the system bus, and a driver circuit (driver) for activating the port signals on the local side, as shown in FIG. 22. The interface circuit is not always in an operative state, but is adapted to be operated only by signals from the local side. Consequently, the interface circuit effectively acts as a buffer, which prevents the noise generated at the time of port signal connection propagating to the system bus. In other words, the port signals can be connected or disconnected when active. On the other hand, the system bus includes bus signals which are always in an operative state (a state in which a signal is present), such as the data and clock lines. Accordingly, if active connection or disconnection of the system bus is attempted, the normal waveforms of the bus signals are disturbed, and, as a result, the hardware can be damaged, the system can shut down, or data in transmission can be corrupted, causing the system to crash. In addition, the IDE.sub.-- HDD control signal, PCMCIA control signal, FDD signal, and LCD panel control signal, cannot be connected or disconnected with power on since they always include a signal in an operative state and may conflict with existing resources within the host. Moreover, from a software perspective, the system configuration of the docking device may conflict with the resources already installed on the host, which would result in a malfunction. Thus, the active connection or disconnection of bus signals can create both hardware and software malfunctions.
Accordingly, in conventional systems, the docking of a portable computer and docking device is permitted only when the portable computer is powered off and the system is not installed. Even when operating in a power management mode which extends the operating time of the self-contained battery, the portable computer could not be docked with the docking device since the power is not completely shut off. In addition, in case a user attempted docking despite the portable computer being powered-on, many conventional systems include a fail safe for which the operations are described below and illustrated in Table 1.
TABLE 1 ______________________________________ State of host before docking Operation in docking ______________________________________ Ordinary operation state or Forcibly shut down the power supply of Standby mode the host to prevent hardware damage to the equipment. Suspend mode After docking, inhibit the host from being resumed, and issue a warning (beep) to indicate disallowing of docking. Power off After docking, perform an ordinary operation with the power being turned on. ______________________________________
In summary, the portable computer and the docking device could not be smoothly docked when the portable computer was in a power-on state.
Incidentally, standby and suspend are part of the power management (PM) operations which have recently become available on portable computers. The standby mode is a mode in which the power is shut down only for particular devices such as a liquid crystal display (LCD), while the system bus remains active. The suspend mode is a mode in which the system bus is inactive and the power for components other than the main memory is shut down after the data necessary for resuming a task is saved in the main memory. To return from the suspend mode to the ordinary operation state is called resume. Such power management operations are performed, for instance, by a program called PM code (loaded into the memory when the system is initiated).
However, among the devices connected through the signal port having the capability of active connection or disconnection, there are some which the user desires to promptly use while the portable computer is in an operating state. For instance, a document of a program being edited on the portable computer may be printed at once by the printer connected to the docking device. Also, a coordinate input using the mouse connected to the docking device may be desired. Even in the event that an operation which the user desires to be immediately performed occurs, if the user must perform a lengthy procedure that requires temporarily turning off the power of the portable computer before making connection, the user may perceive that the docking device is difficult to use.